Acres of Cropland Converted to Developed Land, 1982-1992

Description

This shaded polygon map shows the amount of cropland converted to developed land between 1982 and 1992 within each 8-digit hydrologic unit. The acres converted are presented in five categories based on the following divisions: 20,000 or more acres, 5,000 to 20,000 acres, 2,000 to 5,000 acres, and less than 2,000 acres. A total of 3,955,700 acres were converted. Developed land includes urban and built-up areas and rural transportation land. Metropolitan Statistical Areas are indicated by black squares. Areas with 95% or more Federal area are shaded gray.

Cautions for this Product:
This map does not show the total amount of cropland or developed land. Data are not collected on Federal land. Data are not available for Alaska or the Pacific Basin. Data for Puerto Rico and the U.S. Virgin Islands are shown by 6-digit hydrologic unit.

Sources

Source:National Resources Inventory, 1997Distributor: USDA-NRCS-RIADReliability:
NRI sample data are generally reliable at the 95% confidence interval for state and certain broad substate area analyses. Generally, analyses that aggregate data points by smaller geographic areas and/or more specific criteria result in fewer data points for each aggregation and therefore less reliable estimates. NRI maps reflect national patterns rather than site- specific information.

Layers

Definitions

Cropland:
A Land cover/use category that includes areas used for the production of adapted crops for harvest. Two subcategories of cropland are recognized: cultivated and noncultivated. Cultivated cropland comprises land in row crops or close-grown crops and also other cultivated cropland, for example, hayland or pastureland that is in a rotation with row or close-grown crops. Noncultivated cropland includes permanent hayland and horticultural cropland. [NRI-97]

Developed land:
A combination of land cover/use categories, Urban and built-up areas, and Rural Transportation Land.

Federal land:
A land ownership class designating land that is owned by the Federal Government. It does not include, for example, trust lands administered by the Bureau of Indian Affairs nor Tennessee Valley Authority (TVA) land. No data are collected for any year that land is in this ownership. [NRI-97]

Hydrologic units:
A hierarchical system developed by the U.S. Geological Survey that divides the United States and the Caribbean into 21 major regions, 222 subregions, 352 accounting units, and further subdivided into 2,150 cataloging units that delineate river basins having drainage areas usually greater than 700 square miles. [USGS]

Metropolitan Statistical Areas:
Generally, these are defined as areas that include counties with central cities of 250,000 or more inhabitants (for additional details, contact Bureau of the Census)

Rural transportation land:
A Land Cover/Use category which consists of all highways, roads, railroads and associated rights- of-way outside urban and built-up areas; including private roads to farmsteads or ranch headquarters, logging roads, and other private roads, except field lanes. [NRI-97]

Urban and built-up areas:
A Land Cover/Use category consisting of residential, industrial, commercial, and institutional land; construction sites; public administrative sites; railroad yards; cemeteries; airports; golf courses; sanitary landfills; sewage treatment plants; water control structures and spillways; other land used for such purposes; small parks (less than 10 acres) within urban and built-up areas; and highways, railroads, and other transportation facilities if they are surrounded by urban areas. Also included are tracts of less than 10 acres that do not meet the above definition but are completely surrounded by Urban and Built-up land. Two size categories are recognized in the NRI: (i) areas 0.25 to 10 acres, and (ii) areas greater than 10 acres. [NRI-97]